The closest prior art is the Applicant's own plasma treater which is used to prepare the surface of a substrate before submission to the coating process, and this treater is also called plasma pre-treater. This prior art plasma treater incorporates two cylindrical electrodes surrounding a magnetic means. The cylindrical electrodes are fixed relative to their casing. The known pre-treater generates a plasma cloud using a magnetic array, a reactive gas, an inert gas and a medium frequency alternating current (AC) power applied to an electrode.
By arranging that the substrate passes in close proximity to the electrode, plasma interacts with the surface of the substrate by removing moisture and other contaminants. It also acts to increase the number of nucleation sites through the introduction of polar groups, resulting in an improvement of the coating process with homogeneous surface morphology and less defects.
There is a further known plasma treater which is used to prepare the surface of a substrate for the process following the coating process, and this treater is also called plasma post-treater. A post treatment allows, for example, unwanted particles to be removed from the coated substrate by the method of sputtering.
Unfortunately, the treater of the prior art has a number of drawbacks. It requires regular maintenance after a period of process due to the electrode tube being “dirtied” by the plasma deposits. These deposits can cause arcing which can result in the closing down of the power supply units which incorporate means for detecting this condition.
This maintenance requires the electrode tubes to be cleaned in order to remove the deposits. The preferred method of removal is a manual method using various abrasive materials.
One of the problems which the inventive concept addresses is how to avoid or at least minimise these frequent and labour intensive maintenance cycles.